text: As shown in Scheme 3, diol 19 was protected with phosgene as a carbonate ester (20). The terminal alkene group of 20 was next converted to a methyl ester using ozonolysis followed by oxidation with potassium permanganate and esterification with diazomethane. Ring expansion to give the cyclohexane C ring 24 was achieved using a Dieckman condensation of lactone 23 with lithium diisopropylamide as a base at -78 °C. Decarboxylation of 24 required protection of the hydroxyl group as the 2-methoxy-2-propyl (MOP) ether (25). With the protecting group in place, decarboxylation was effected with potassium thiophenolate in dimethylformamide to give protected hydroxy ketone 26. In the next two steps the MOP protecting group was removed under acidic conditions, and alcohol 27 was reprotected as the more robust benzyloxymethyl ether 28. The ketone was converted to the trimethylsilyl enol ether 29, which was subsequently oxidized in a Rubottom oxidation using m-chloroperbezoic acid to give the trimethylsilyl protected acyloin 30. At this stage the final missing carbon atom in the Taxol ring framework was introduced in a Grignard reaction of ketone 30 using a 10-fold excess of methylmagnesium bromide to give tertiary alcohol 31. Treatment of this tertiary alcohol with the Burgess reagent (32) gave exocyclic alkene 33.